CrossBread
I downloaded the original .capx from you, and opened the .caproj in a text editor with line numbers.
Delete lines: 25 (reference to plugin), 378/379/380 (object-type reference), 448 (instance reference).
Save and then try to open. It opens fine for me. If yours doesn't. I'll upload to my Dropbox, but this is a useful thing to get your head around (and your hands dirty).